This invention generally relates to a chewable object which has an enjoyable flavor or exhibits an attractive odor.
Chewable objects perform a number of useful functions for pets, such as dogs and cats, namely, they provide exercise for the pets' jaw muscles, they massage the pets' gums and thus clean the pets' teeth. Young children also find such objects useful, particularly during periods of tooth eruption, in order to obtain relief by chewing on a firm but pliable object.
A variety of materials have been used for such chewable objects in the past. For example, rawhide, woven fabrics, or rope have been used but they are subject to breakdown from continued chewing and as a result they have not been found to be very satisfactory. More stable materials, such as rubber or plastic have also been utilized, to make chewable toys but frequently these materials have undesirable tastes.
Odor or flavor components have been applied to the surface of chewable objects to increase the attractiveness thereof, but these superficial flavors or odors quickly dissipate due to the exposure to the atmosphere or to chewing.
Methods have been developed (see U.S. Pat. No. 3,871,334 to Axelrod) to impregnate a chewable object formed from nylon with an aqueous-based flavor or odor extract and the chewable objects so treated have achieved substantial commercial success. However, nylon tends to be hard and relatively stiff, particularly during cold weather and furthermore it has a tendency to splinter and fray when subjected to vigorous mastication. Young animals find flavor-impregnated nylon objects very attractive but as the animals mature, they tend to discontinue chewing or otherwise playing with such nylon objects. The loss of interest has been attributed to the hardness of such nylon objects.
Edwards in U.S. Pat. No. 4,513,014 sought to provide a more chewable product comprising a polyurethane elastomer having incorporated therein flavor or odor extracts dissolved in an oil or wax carrier. These polyurethane products were designed so that the oil or wax-based flavor or odor extracts incorporated into the elastomer body bleed to the surface of the product so the flavor or odor lasts over an extended period. However, the oil or wax-based flavor or odor extracts which bleed to the surface readily rub off onto furniture, rugs, and the like, and, as a result, such objects were not very desirable for in-house use. The flavor or odor extracts also come off when the objects are manually handled such as when the pet owner plays with the object with his or her pet. It should be particularly noted that prior chewable objects have a very storng disagreeable ordor. Such odor is disliked by both pet store dealers and pet owners.
In the process described by Edwards the flavor or odor extracts are incorporated within the body of the polyurethane during the polymerization thereof or when the product was injection molded or otherwise formed. These processes may involve temperatures well above 300.degree. F., which can change the flavors or odors considerably and while the flavors or odors therefrom may be attractive to the pets, they would not always be acceptable to the pet owner. It has also been found that by incorporating the oil or wax based flavors or odors into the polyurethane the physical and mechanical properties of the cured products were significantly reduced.
Nylon can absorb up to 8% by weight or more of water but polyurethanes and other plastic materials have a very low propensity to absorb water less than about 2%. As a result polyurethane has not been considered to be appropriate substrate for impregnation with water based odor or flavor extracts.
As a result, there has been a long-felt need for an improved, more chewable object having both an attractive flavor or odor and sufficient physical properties to avoid destruction when chewed. The present invention fulfills this need and provides further advantages.